The present invention relates to semiconductor manufacturing, and more particularly, to systems and methods of real-time control of processing tools.
FIGS. 1a and 1b illustrate operation of a conventional advanced process control (APC). FIG. 1a schematically shows a chemical mechanical polishing (CMP) fabrication system implementing APC. A CMP station 100 comprises three individual operable CMP platens 101, 102 and 103. A process controller 110 is operatively connected to the CMP station 100. The process controller 110 is configured to receive information from a metrology tool 120 and from the CMP station 100. Additionally, the process controller 110 may receive information pertaining to a product 130 to be processed by the CMP station 100, and information pertaining to a process recipe 140 specifying process settings of CMP station 100.
FIG. 1b is a flowchart illustrating the operation of the fabrication system shown in FIG. 1a. In step S150, an initial process state is determined. Here, a process state represents a removal rate at each of the CMP platens 101, 102 and 103. The process state may also represent the removal rate and the associated degree of dishing and erosion at each of the CMP platens 101, 102 and 103, or a total removal rate of the CMP station 100. The product 130 is then processed with process settings adjusted on the basis of the initial process state.
In step S155, a current process state is determined according to a preset process model and historical information received from metrology tool 120, CMP station 100, a product 130 to be processed and a corresponding process recipe. Generally, measurement results obtained from the metrology tool 120 may be delayed or may not be available unless a plurality of products 130 is completely processed.
In step S160, one or more control wafer is processed, and the process state is adjusted accordingly.
In step S165, a new process state is determined from a previous process state.
In step S170, it is determined whether a reset event occurs. The process flow continuously updates the process state when no reset event occurs. For example, the reset event occurs when the lifetime of a consumable has expired or will soon expire, a polishing head has to be replaced, a machine failure has occurred, the type of product is to be changed, or the process recipe has to be changed, and the like. Any of these events may render the process state unpredictable and, therefore, process controller 110 is re-initialized with the initial state set in advance and the process continues as depicted in FIG. 1b on the basis of newly gathered history information after the reset event.
Hence, a system that addresses problems arising from the existing technology is desirable.